Spinach Gratin

This recipe has become a staple of Thanksgiving at our house and a must-make every year.

Ingredients

• 4 tbsp (1/2 stick) unsalted butter
• 4 cups chopped yellow onions (2 large)
• 1/4 cup flour
• 1/4 tsp grated nutmeg
• 1 cup heavy cream
• 2 cups milk
• 3 lbs frozen chopped spinach, defrosted (5 ten-ounce packages)
• 1 cup freshly grated Parmesan cheese
• 1 tbsp kosher salt
• 1/2 tsp freshly ground black pepper
• 1/2 cup grated Gruyere cheese

Instructions

1. Preheat oven to 425°F.
2. Melt butter in a heavy pan over medium heat. Cook onions until soft, roughly 15 minutes. Stir in flour and nutmeg for 2 minutes. Add cream and milk, cook until it thickens. Squeeze excess liquid from spinach and combine with sauce.
3. Mix in half the Parmesan cheese. Season with salt and pepper to preference.
4. Transfer mixture to a baking dish. Top with remaining Parmesan and Gruyere.
5. Bake for 20 minutes until bubbling and heated through. Serve immediately.